I have a lemon tree grown from unknown source (birds,people..) it is as healthy as can be but hasn;t flowered/fruited.I am wondering if it is possible to graft a known variety on too the trunk/branch to produce mandarines or limes etc tree is approx 12 years old and 2 metres tall with a rough trunk diamater of 10 cm. Any help would be very much appreciated.Cheers